Melt 4 tablespoons butter and mix it well with 1 1/3 cup vanilla wafer crumbs. Press firmly and evenly over the bottom and sides of a 9-inch pie plate, building the mixture up around the rum. Chill well.

Mix 2 tablespoons unflavored gelatin with 1/2 cup of sugar in a saucepan. Add 1 cup water and cook over low heat, stirring constantly, until the gelatin is dissolved. Spoon 1 pint yogurt into a bowl and gradually beat in 1 (6 oz.) can thawed orange juice concentrate. Stir in the gelatin mixture and beat until smooth. Beat 2 egg whites with 2 tablespoons sugar until stiff peaks form.

Fold a quarter of this meringue into the orange mixture, then fold in the remaining meringue. Chill this until the mixture mounds when dropped from a spoon. Turn into the prepared crust and chill until firm. Garnish with toasted coconut.